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Saturday, 02 April 2011 22:04

Woodworking Processes

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For the purposes of this article, the processes of the woodworking industry will be considered to start with the reception of converted timber from the sawmill and continue until the shipping of a finished wood article or product. Earlier stages in the handling of wood are dealt with in the chapters Forestry and Lumber industry.

The woodworking industry produces furniture and a variety of building materials, ranging from plywood floors to shingles. This article covers the main stages in the processing of wood for the production of wooden products, which are machine working of natural wood or manufactured panels, assembly of machined parts and surface finishing (e.g., painting, staining, lacquering, veneering and so on). Figure 1 is a flow diagram for wood furniture manufacturing, which covers nearly the whole range of these processes.

Figure 1. Flow diagram for wood furniture manufacturing

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Drying. Some furniture manufacturing facilities may purchase dried lumber, but others perform drying onsite using a drying kiln or oven, fired by a boiler. Usually wood waste is the fuel.

Machining. Once the lumber is dried, it is sawed and otherwise machined into the shape of the final furniture part, such as a table leg. In a normal plant, the wood stock moves from rough planer, to cutoff saw, to rip saw, to finish planer, to moulder, to lathe, to table saw, to band saw, to router, to shaper, to drill and mortiser, to carver and then to a variety of sanders.

Wood can be hand carved/worked with a variety of hand tools, including chisels, rasps, files, hand saws, sandpaper and the like.

In many instances, the design of furniture pieces requires bending of certain wooden parts. This occurs after the planing process, and usually involves the application of pressure in conjunction with a softening agent, such as water, and increased atmospheric pressure. After bending into the desired shape, the piece is dried to remove excess moisture.

Assembly. Wood furniture can either be finished and then assembled, or the reverse. Furniture made of irregularly shaped components is usually assembled and then finished.

The assembly process usually involves the use of adhesives (either synthetic or natural) in conjunction with other joining methods, such as nailing, followed by the application of veneers. Purchased veneers are trimmed to correct size and patterns, and bonded to purchased chipboard.

After assembly, the furniture part is examined to ensure a smooth surface for finishing.

Pre-finishing. After initial sanding, an even smoother surface is attained by spraying, sponging or dipping the furniture part with water to cause the wood fibres to swell and “raise”. After the surface has dried, a solution of glue or resin is applied and allowed to dry. The raised fibres are then sanded down to form a smooth surface.

If the wood contains rosin, which can interfere with the effectiveness of certain finishes, it may be derosinated by applying a mixture of acetone and ammonia. The wood is then bleached by spraying, sponging or dipping the wood into a bleaching agent such as hydrogen peroxide.

Surface finishing. Surface finishing may involve the use of a large variety of coatings. These coatings are applied after the product is assembled or in a flat line operation before assembly. Coatings could normally include fillers, stains, glazes, sealers, lacquers, paints, varnishes and other finishes. The coatings may be applied by spray, brush, pad, dip, roller or flow-coating machine.

Coatings can be either solvent based or water based. Paints may contain a wide variety of pigments, depending on the desired colour.

Hazards and Precautions

Machining safety

Woodworking manufacturing has many of the hazards to safety and health that are common to general industry, with a much larger proportion of extremely hazardous equipment and operations than most. Consequently, safety requires constant attention to safe work habits by employees, vigilant supervision, and maintenance of a safe work environment by employers.

Although in many instances woodworking machinery and equipment may be purchased without the necessary guards and other safety devices, it is management’s responsibility to provide adequate safeguards before such machinery and equipment is used. See also the articles “Routing machines” and “Wood planing machines”.

Sawing machines. Employees should be made aware of the safe operating practices necessary for the proper use of various woodworking saws (see figure 2 and figure 3).

Figure 2. Band saw

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Figure 3. Table saw

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Specific guidelines are as follows:

1. When feeding a table saw, hands must be kept out of the line of the cut. No guard can prevent a person’s hand from following the stock into the saw. When ripping with the fence gauge near the saw, a push stick or suitable jig must be used to complete the cut. See figure 4.

Figure 4. Push sticks

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2. The saw blade must be positioned so as to minimize its protrusion above the stock; the lower the blade, the less chance for kickbacks. It is good practice to stand out of the line of the stock being ripped. A heavy leather apron or other guard for the abdomen is recommended.

3. Freehand sawing is always dangerous. The stock must always be held against a gauge or fence. See figure 3.

4. The saw must be appropriate for the job. For instance, it is an unsafe practice to rip with a table saw not equipped with a non-kickback device. Kickback aprons are recommended.

5. The dangerous practice of removing a hood guard because of narrow clearance on the gauge side can be avoided by clamping a filler board to the table between the gauge and the saw and using it to guide the stock. Employees must never be permitted to bypass guards. Combs, featherboards (see figure 5) or suitable jigs must be provided where standard guards cannot be used.

Figure 5. Featherboards & combs

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6. Crosscutting long boards on a table saw should be avoided because the operator is required to use considerable hand pressure near the saw blade. Also, boards extending beyond the table may be struck by people or trucks. Long stock should be crosscut on a swing pull saw or radial arm saw with adequate supporting bench.

7. Work that should be done on special power-feed machines should not be done on general-purpose hand-fed machines.

8.To set a gauge of a table saw without taking off the guards, a permanent mark should designate the line of cut on the table top.

9. It is considered safe practice to bring equipment to a complete stop before adjusting blades or fences, and to disconnect the power source when changing blades.

10. A brush or stick should be used to clean sawdust and scrap from a saw.

A table saw is also called a variety saw because it can perform a wide variety of sawing functions. For this reason the operator should have a variety of guards, because no one guard can protect from every function. See figure 3.

Cutting machines. Cutting machines can also be hazardous if not adequately guarded and always used with respect and alertness. Cutting tools should be kept well sharpened and correctly balanced on their spindles.

The router shown in figure 6 has a brush guard. Other routers may have a ring guard, a round guard that encircles the router bit. The purpose of guards is to keep the hands away from the cutting bit. Computer numerical controlled (CNC) routers may have several bits and are high production machines. On CNC machines the operator’s hands are kept further from the bit area. However, another problem is the high amount of wood dust. See also the article “Routing machines”.

Figure 6. Router

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Guarding on a jointer or surface planing machine is mainly to keep the operator’s hands away from the revolving knives. The “mutton chop”-type guard allows only the portion of the knives which are cutting the stock to be exposed (see figure 7). The exposed portion of the knives behind the fence should also be guarded.

Figure 7. Jointer

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The shaper is a potentially very dangerous machine (see figure 8). If the shaper knives become separated from the above and below collars on the arbor, they can be thrown with great force. Also, stock must often be held close to the knives. This holding must be done with a fixture instead of by the operator’s hands. Featherboards can be used to hold the stock down against the table. Ring or saucer guards should be used whenever possible. A saucer guard is a round, flat, plastic disk that is mounted horizontally on the arbor above the shaper knives.

Figure 8. Shaper

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A lathe should be guarded by a hood guard because there is a danger of the stock being thrown from the machine. See figure 9. It is good practice for the hood to be interlocked with the motor so the lathe cannot be run unless the hood guard is in place.

Figure 9. Lathe

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A ripsaw should have anti-kickback fingers installed to prevent the stock from reversing its direction and striking the operator. See figure 10. Also, the operator should wear a padded apron to lessen the impact if a kickback does occur.

Figure 10. Ripsaw

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Because the radial arm saw blade can be tilted sideways, a guard must be used which will not lie into the blade. See figure 11.

Figure 11. Radial arm saw

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Sanding machines. Machined stock pieces are sanded down using belt, jitterbug, disc, drum or orbital sanders. Nip points are created in sanding belts. See figure 12. Often these nip points can be guarded with a hood which will also be part of a dust exhaust system.

Figure 12. Sander

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Machine guarding. Figure 13 illustrates that the opening between a guard and the point of contact must be decreased as the distance decreases.

Figure 13. Distance between guard & point of  operation

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Miscellaneous machine safety concerns. Care must be taken that the use of stock-clamping/holding devices do not create additional hazards.

Most woodworking machines create the necessity of the operator (and helper) wearing eye protection.

It is common practice for employees to blow dust off of themselves with compressed air. They should be cautioned to keep air pressure below 30 psi and to avoid blowing into eyes or open cuts.

Wood dust hazards

Machines that produce wood dust should be equipped with dust-collecting systems. If the exhaust system is inadequate to dispose of the wood dust, the operator may need to wear a dust respirator. The International Agency for Research on Cancer (IARC) has now determined that “there is sufficient evidence in humans for the carcinogenicity of wood dust”, and that “Wood dust is carcinogenic to humans (Group 1)”. Other studies indicate that wood dust may prove an irritant to the mucous membranes of the eyes, nose and throat. Some toxic woods are more actively pathogenic and may produce allergic reactions and occasionally pulmonary disorders and systemic poisoning. See table 1.

Table 1. Poisonous, allergenic and biologically active wood varieties

Scientific names

Selected commercial names

Family

Health Impairment

Abies alba Mill (A. pectinata D.C.) 

Silver fir

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Acacia spp.
A. harpophylla
F. Muell.
A. melanoxylon
R. Br.
A. seyal
Del.
A. shirley
Maiden 

Australian blackwood

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Acer spp.
A. platanoides
L.

Maple

Aceraceae

Dermatitis

Afrormosia elata Harms.
(Pericopsis elata
Van Meeuwen)

Afrormosia, kokrodua, asamala, obang, oleo pardo, bohele, mohole

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Afzelia africana Smith
A. bijuga
A. Chev. (Intsia bijuga A. Cunn.)
A. palembanica
Bak. (Intsia palembanica Bak.)

Doussié, afzelia, aligua, apa, chanfuta, lingue merbau, intsia, hintsy

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Agonandra brasiliensis Miers 

Pao, marfim, granadillo

Olacaceae

Dermatitis

Ailanthus altissima Mill 

Chinese sumac

Simaroubaceae

Dermatitis

Albizzia falcata Backer
A. ferruginea Benth.
A. lebbek Benth
A. toona F.M. Bail 

Iatandza


Kokko, siris

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma;
toxic effects

Alnus spp.
A. glutinosa
Gaertn.

Common alder
Black alder

Betulaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Amyris spp.
A. balsamifera
L.
A. toxifera
Willd. 

Venezuelan or West Indian sandalwood

Rutaceae

Dermatitis; toxic effects

Anacardium occidentale L.
A. excelsum
Skels.

Cashew

Anacardiaceae

Dermatitis

Andira araroba Aguiar. (Vataireopsis araroba Ducke)
A. coriacea
Pulle
A. inermis
H.B.K. 

Red cabbage tree

Partridge wood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Aningeria spp.
A. robusta
Aubr. and Pell.
A. altissima
Aubr. and Pell.
Antiaris africana
Engl.
A. welwitschi
Engl.

Aningeria

Antiaris, ako, chen chen

Sapotaceae

Moraceae

Conjunctivitis-rhinitis; asthma

Toxic effects

Apuleia molaris spruce (A. leiocarpa MacBride)
(A. ferrea
Mart.)

Redwood

Caesalpinaceae

Dermatitis; toxic effects

Araucaria angustifolia O. Ktze
A. brasiliana
A. Rich.

Parana pine, araucaria

Araucariaceae

Toxic effects

Aspidosperma spp.
A. peroba
Fr. All.
A. vargasii
A. DC.

Red peroba

Pau marfim, pau amarello, pequia marfim, guatambu, amarilla, pequia

Apocynaceae

Dermatitis; conjunctivitis-
rhinitis; asthma; toxic effects

Astrocaryum spp.

Palm

Palmaceae

Dermatitis; toxic effects

Aucoumea klaineana Pierre 

Gabon mahogany

Burseraceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Autranella congolensis
A. Chev. (Mimusops congolensis
De Wild.)

Mukulungu, autracon, elang, bouanga, kulungu

Sapotaceae

Dermatitis

Bactris spp. (Astrocaryum spp.)

Palm

Palmaceae

Dermatitis; toxic effects

Balfourodendron riedelianum Engl.

Guatambu, gutambu blanco

Rutaceae

Dermatitis

Batesia floribunda Benth.

Acapu rana

Caesalpinaceae

Toxic effects

Berberis vulgaris L.

Barberry

Berberidaceae

Toxic effects

Betula spp.
B. alba
L. (B. pendula Roth.)

Birch

Betulaceae

Dermatitis

Blepharocarva involucrigera F. Muell. 

Rosebutternut

Anacardiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Bombax brevicuspe Sprague
B. chevalieri
Pell 

Kondroti, alone

Bombacaceae

Dermatitis

Bowdichia spp.
B. nitida
Benth.
B. guianensis
Ducke (Diplotropis guianensis Benth.)
(Diplotropis purpurea
Amsh.)

Black sucupira

Papilionaceae

Dermatitis

Brachylaena hutchinsii Hutch.

Muhuhu

Compositae

Dermatitis

Breonia spp.

Molompangady

Rubiaceae

Dermatitis

Brosimum spp.
B. guianense
Hub. (Piratinera guianensis Aubl.)

Snakewood, letterwood, tigerwood

Moraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Brya ebenus DC. (Amerimnum ebenus Sw.)
Brya buxifolia
Urb.

Brown ebony, green ebony, Jamaican ebony, tropical American ebony

Papilionaceae

Dermatitis

Buxus sempervirens L.
B. macowani
Oliv.

European boxwood, East London b., Cape b.

Buxaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Caesalpinia echinata Lam. (Guilandina echinata Spreng.)

Brasilwood

Caesalpinaceae

Dermatitis; toxic effects

Callitris columellaris F. Muell.

White cypress pine

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Calophyllum spp.
C. brasiliense
Camb.

Santa maria, jacareuba, kurahura, galba

Guttiferae

Dermatitis; toxic effects

Campsiandra laurifolia Benth.

Acapu rana

Caesalpinaceae

Toxic effects

Carpinus betulus

Hornbeam

Betulaceae

Dermatitis

Cassia siamea Lamk.

Tagayasan, muong ten, djohar

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Castanea dentata Borkh
C. sativa
Mill.
C. pumila
Mill.

Chestnut, sweet chestnut

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Castanospermum australe A. Cunn.

Black bean, Australian or Moreton Bay chestnut

Papilionaceae

Dermatitis

Cedrela spp. (Toona spp.)

Red cedar, Australian cedar

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Cedrus deodara (Roxb. ex. Lamb.) G. Don
(C. libani
Barrel. lc)

Deodar

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Celtis brieyi De Wild.
C. cinnamomea
Ldl.

Diania
Gurenda

Ulmaceae

Dermatitis

Chlorophora excelsa Benth. and Hook I.
C. regia
A. Chev.
C. tinctoria
(L.) Daub.

Iroko, gelbholz, yellowood, kambala, mvule, odum, moule, African teak, abang, tatajuba, fustic, mora

Moraceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Chloroxylon spp.
C. swietenia
A.DC. 

Ceylon satinwood

Rutaceae

Dermatitis; toxic effects

Chrysophyllum spp.

Najara

Sapotaceae

Dermatitis

Cinnamomum camphora Nees and Ebeim 

Asian camphorwood, cinnamon

Lauraceae

Toxic effects

Cryptocarya pleurosperma White and Francis 

Poison walnut

Lauraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Dacrycarpus dacryoides (A. Rich.) de Laub. 

New Zealand white pine

Podocarpaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Dacrydium cupressinum Soland 

Sempilor, rimu

Podocarpaceae

conjunctivitis-rhinitis; asthma

Dactylocladus stenostachys Oliv.

Jong kong, merebong, medang tabak

Melastomaceae

Toxic effects

Dalbergia spp.
D. amerimnon
Benth.
D. granadillo
Pitt.
D. hypoleuca
Standl.
D. latifolia
Roxb.
D. melanoxylon
Guill. and Perr.
D. nigra
Fr. All.


D. oliveri
Gamble
D. retusa
Hemsl.
D. sissoo
Roxb.
D. stevensonii
Standl.

Ebony

Red foxwood

Indian rosewood, Bombay blackwood, African blackwood, pallisander, riopalissandro, Brasilian rosewood, jacaranda

Burma rosewood
Red foxwood
Nagaed wood, Honduras rosewood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma;
toxic effects

Dialium spp.
D. dinklangeri
Harms.

Eyoum, eyum

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Diospyros spp.
D. celebica
Bakh.
D. crassiflora
Hiern
D. ebenum
Koenig 

Ebony, African ebony

Macassar ebony, African ebony, Ceylon ebony

Ebenaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Dipterocarpus spp.
D. alatus
Roxb.

Keruing, gurjum, yang, keruing

Dipterocarpaceae

Dermatitis

Distemonanthus benthamianus Baill.

Movingui, ayan, anyaran, Nigerian satinwood

Caesalpinaceae

Dermatitis

Dysoxylum spp.
D. fraseranum
Benth.

Mahogany, stavewood, red bean

Meliaceae

dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

D. muelleri Benth.

Rose mahogany

   

Echirospermum balthazarii Fr. All. (Plathymenia reticulata Benth.)

Vinhatico

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Entandophragma spp.
E. angolense
C.D.C.
E. candollei
Harms.
E. cylindricum
Sprague
E. utile
Sprague 

Tiama
Kosipo, omo
Sapelli, sapele, aboudikro
Sipo, utile, assié,
kalungi, mufumbi

Meliaceae

Dermatitis;
allergic extrinsic alveolitis

Erythrophloeum guineense G. Don
E. ivorense
A. Chev. 

Tali, missanda, eloun, massanda, sasswood, erun, redwater tree

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Esenbeckia leiocarpa Engl.

Guaranta

Rutaceae

Dermatitis

Eucalyptus spp.
E. delegatensis
R.T. Back
E. hemiphloia
F. Muell.
E. leucoxylon
Maiden
E. maculata
Hook.
E. marginata
Donn ex Sm.
E. microtheca
F. Muell.
E. obliqua
L. Herit.
E. regnans
F. Muell.
E. saligna
Sm.


Alpine ash
Grey box
Yellow gum
Spotted gum



Mountain ash

Myrtaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Euxylophora paraensis Hub.

Boxwood

Rutaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Excoecaria africana M. Arg. (Spirostachys africana Sand)
E. agallocha
L. 

African sandalwood, tabootie, geor, aloewood, blind-your-eye

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Fagara spp.
F. flava
Krug and Urb. (Zanthoxylum flavum Vahl.)
F. heitzii
Aubr. and Pell.
F. macrophylla
Engl.

Yellow sanders, West Indian satinwood, atlaswood, olon, bongo, mbanza

Rutaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Fagus spp. (Nothofagus spp.)
F. sylvatica
L. 

Beech

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Fitzroya cupressoides (Molina) Johnston
(
F. patagonica Hook. f.)

Alerce

Cupressaceae

Dermatitis

Flindersia australis R. Br.
F. brayleyana
F. Muell.
F. pimenteliana
F. Muell.

Australian teak, Queensland maple, maple
Silkwood, Australian maple

Rutaceae

Dermatitis

Fraxinus spp.
F. excelsior
L. 

Ash

Oleaceae

Dermatitis

Gluta spp.
G. rhengas
L. (Melanorrhoea spp.)
M. curtisii
Pierre
M. laccifera wallichii
Hook.

Rengas, gluta
Renga wood
Rhengas

Anacardiaceae

Dermatitis; toxic effects

Gonioma kamassi E. Mey.

Knysna boxwood, kamassi

Apocynaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Gonystylus bancanus Baill.

Ramin, melawis, akenia

Gonystylaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Gossweilerodendron balsamiferum (Verm.) Harms.

Nigerian cedar

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Grevillea robusta A. Cunn.

Silky oak

Proteaceae

Dermatitis

Guaiacum officinale L.

Gaiac, lignum vitae

Zygophyllaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Guarea spp.
G. cedrata
Pell.

G. laurentii
De Wild.
G. thompsonii
Sprague

Bossé
Nigerian pearwood Cedar mahogany
Scented guarea
Black guarea

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Halfordia scleroxyla F. Muell.
H. papuana
Lauterb.

Saffron-heart

Polygonaceae

Dermatitis; allergic extrinsic alveolitis

Hernandia spp.
H. sonora
L. (H. guianensis Aubl.)

Mirobolan, topolite

Hernandiaceae

Dermatitis

Hippomane mancinella L.

Beach apple

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Illipe latifolia F. Muell.
I. longifolia
F. Muell. (Bassia latifolia Roxb.) (B. longifolia Roxb.)

Moak, edel teak

Sapotaceae

Dermatitis

Jacaranda spp.
J. brasiliana
Pers. Syn. (Bignonia brasiliana Lam.)
J. coerulea
(I.) Gris.

Jacaranda

Caroba, boxwood

Bignoniaceae

Dermatitis

Juglans spp.
J. nigra
L.
J. regia
L.

Walnut

Juglandaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Juniperus sabina L.
J. phoenicea
L.
J. virginiana
L.



Virginian pencil cedar, Eastern red cedar

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Khaya antotheca C. DC.

K. ivorensis
A. Chev.
K. senegalensis
A. Juss.

Ogwango, African mahogany, krala

Dry-zone mahogany

Meliaceae

Dermatitis; allergic extrinsic alveolitis

Laburnum anagyroides Medic. (Cytisus laburnum L.)
L. vulgare
Gris

Laburnum

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Larix spp.
L. decidua
Mill.
L. europea
D.C.

Larch
European larch

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Liquidambar styracifolia L.

Amberbaum, satin-nussbaum

Hamamelidaceae

Dermatitis

Liriodendron tulipifera L.

American whitewood, tulip tree

Magnoliaceae

Dermatitis

Lovoa trichilioides Harms. (L. klaineana Pierre)

Dibetou, African walnut, apopo, tigerwood, side

Meliaceae

dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Lucuma spp. (Pouteria spp.)
L. procera

Guapeva, abiurana
Massaranduba

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Maba ebenus Wight.

Makassar-ebenholz

Ebenaceae

Dermatitis

Machaerium pedicellatum Vog.
M. scleroxylon
Tul.
M. violaceum
Vog.

Kingswood

Papilionaceae

Dermatitis

Mansonia altissima A. Chev.

Nigerian walnut

Sterculiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Melanoxylon brauna Schott

Brauna, grauna

Caesalpinaceae

Dermatitis

Microberlinia brazzavillensis A. Chev.
M. bisulcata
A. Chev.

African zebrawood

Caesalpinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Millettia laurentii De Wild.
M. stuhlmannii
Taub.

Wenge
Panga-panga

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma;
toxic effects

Mimusops spp. (Manilkara spp.)
Mimusops
spp. (Dumoria spp.) (Tieghemella spp.)
M. congolensis
De Wild. (Autranella congolensis A. Chev.)
M. djave
Engl. (Baillonella toxisperma Pierre)
M. heckelii
Hutch. et Dalz. (Tieghemella heckelii Pierre
(Dumoria heckelii
A. Chev.)

Muirapiranga
Makoré
Mukulungu, autracon

Moabi
Cherry mahogany

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma;
allergic
extrinsic alveolitis; toxic effects

Mitragyna ciliata Aubr. and Pell.
M. stipulosa
O. Ktze

Vuku, African poplar
Abura

Rubiaceae

Dermatitis; conjunctivitis-rhinitis; asthma;
toxic effects

Nauclea diderrichii Merrill (Sarcocephalus diderrichii De Wild.)
Nauclea trillessi
Merrill

Bilinga, opepe, kussia, badi, West African boxwood

Rubiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Nesogordonia papaverifera R. Capuron

Kotibé, danta, epro, otutu, ovové, aborbora

Tiliaceae

Toxic effects

Ocotea spp.
O. bullata
E. Mey
O. porosa
L. Barr. (Phoebe porosa Mez.)
O. rodiaei
Mez. (Nectandra rodiaei Schomb.)
O. rubra
Mez.
O. usambarensis
Engl.

Stinkwood

Laurel Brazilian walnut
Greenheart
Louro vermelho
East African camphorwood

Lauraceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Paratecoma spp.
P. alba
P. peroba
Kuhlm.


Brazilian white peroba
Peroba white. p.

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Parinarium spp.
P. guianense (Parinari
spp.) (Brosimum spp.)
P. variegatum


Guyana-satinholz
Antillen-satinholz

Rosaceae

Dermatitis

Peltogyne spp.
P. densiflora
Spruce

Blue wood, purpleheart

Caesalpinaceae

Toxic effects

Phyllanthus ferdinandi F.v.M.

Lignum vitae, chow way, tow war

Euphorbiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Picea spp.
P. abies
Karst.
P. excelsa
Link.
P. mariana
B.S.P.
P. polita
Carr.

European spruce, whitewood


Black spruce

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Pinus spp.
P. radiata
D. Don

Pine

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Piptadenia africana Hook f.
Piptadeniastrum africanum
Brenan

Dabema, dahoma, ekhimi
agobin, mpewere, bukundu

Mimosaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Platanus spp.

Plane

Platanaceae

Dermatitis

Pometia spp.
P. pinnata
Forst.

Taun
Kasai

Sapindaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Populus spp.

Poplar

Salicaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Prosopis juliflora D.C.

Cashaw

Mimosaceae

Dermatitis

Prunus spp.
P. serotina
Ehrl.

Cherry
Blackcherry

Rosaceae

dermatitis; conjunctivitis-rhinitis; asthma

Pseudomorus brunoniana Bureau

White handlewood

Moraceae

Dermatitis; toxic effects

Pseudotsuga douglasii Carr. (P. menziesii Franco)

Douglas fir, red fir, Douglas spruce

Pinaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Pterocarpus spp.
P. angolensis
D.C.
P. indicus
Willd.
P. santalinus
L.f. (Vatairea guianensis Aubl.)

African padauk, New Guinea rosewood, red sandalwood, red sanders, quassia wood

Papilionaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Pycnanthus angolensis Warb. (P. kombo Warb.)

Ilomba

Myristicaceae

Toxic effects

Quercus spp.

Oak

Fagaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Raputia alba Engl.
R. magnifica
Engl.

Arapoca branca, arapoca

Rutaceae

Dermatitis

Rauwolfia pentaphylla Stapf. O.

Peroba

Apocynaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Sandoricum spp.
S. indicum
Cav.

Sentul, katon, kra-ton, ketjapi, thitto

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Schinopsis lorentzii Engl.
S. balansae
Engl.

Quebracho colorado, red q., San Juan, pau mulato

Anacardiaceae

Dermatitis; toxic effects

Semercarpus australiensis Engl.
S. anacardium
L.

Marking nut

Anacardiaceae

Dermatitis; toxic effects

Sequoia sempervirens Endl.

Sequoia, California
redwood

Taxodiaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Shorea spp.

Alan, almon, red balau
White heavy, red lauan, white L., yellow L., mayapis, meranti bakau, dark red M., light red M., red M., white M., yellow M., red seraya, white seraya

Dipterocarpaceae

Dermatitis

S. assamica Dyer

Yellow lauan, white meranti

   

Staudtia stipitata Warb. (S. gabonensis Warb.)

Niové

Myristicaceae

Dermatitis

Swietenia spp.
S. macrophylla
King
S. mahogany
Jacq.

Mahogany, Honduras mahogany, Tabasco m., baywood, American mahogany,
Cuban mahogany

Meliaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis; toxic effects

Swintonia spicifera Hook.
S. floribunda
Griff.

Merpauh

Anacardiaceae

Dermatitis

Tabebuia spp.
T. ipe
Standl. (T. avellanedae Lor. ex Gris.)
T. guayacan Hensl. (T. lapacho
K. Schum)

Araguan, ipé preto, lapacho

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Taxus baccata L.

Yew

Taxaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis; toxic effects

Tecoma spp.
T. araliacea
D.C.
T. lapacho

Green heart
Lapacho

Bignoniaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Tectona grandis L.

Teak, djati, kyun, teck

Verbenaceae

Dermatitis; conjunctivitis-rhinitis; asthma; allergic extrinsic alveolitis

Terminalia alata Roth.
T. superba
Engl. and Diels.

Indian laurel
limba, afara, ofram, fraké, korina, akom

Combretaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Thuja occidentalis L.
T. plicata
D. Don
T. standishii
Carr.

White cedar
Western red cedar

Cupressaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Tieghemella africana A. Chev. (Dumoria spp.)
T. heckelii
Pierre

Makoré, douka, okola, ukola, makoré, abacu, baku, African cherry

Sapotaceae

Dermatitis; conjunctivitis-rhinitis; asthma; toxic effects

Triplochiton scleroxylon K. Schum

Obeche, samba, wawa, abachi, African whitewood, arere

Sterculiaceae

Dermatitis; conjunctivitis-rhinitis; asthma

Tsuga heterophylla Sarg.

Tsuga, Western hemlock

Pinaceae

Dermatitis

Turraeanthus africana Pell.

Avodiré
Lusamba

Meliaceae

Dermatitis; allergic extrinsic alveolitis

Ulmus spp.

Elm

Ulmaceae

Dermatitis

Vitex ciliata Pell.

 

Verbenaceae

Dermatitis

V. congolensis De Wild. and Th. Dur

Difundu

   

V. pachyphylla Bak.

Evino

   

Xylia dolabriformis Benth.

 

Mimosaceae

Conjunctivitis-rhinitis;

X. xylocarpa Taub.

Pyinkado

 

asthma

Zollernia paraensis Huber

Santo wood

Caesalpinaceae

Dermatitis; toxic effects

Source: Istituto del Legno, Florence, Italy.

Increased use of high-production CNC machinery such as routers, tenoners and lathes creates more wood dust and will require new dust-collection technology.

Dust control. Most dust in a woodworking production shop is removed by local exhaust systems. However, often there is a considerable accumulation of very fine dust that has settled on rafters and other structural members, especially in areas where sanding is done. This is a hazardous situation, with great potential for fire and explosion. A flash fire over dust-covered surfaces may be followed by explosions of increasing force. In order to minimize this probability, it would be wise to use a checklist. See sample checklist in box.

Assembly hazards

A wide range of adhesives is used in the bonding of veneers to manufactured panels, depending on the characteristics required of the final product. Apart from casein glue, natural adhesives are less widely employed and the greatest use is made of synthetic adhesives such as urea-formaldehyde. Synthetic adhesives may pose a hazard of skin disease or systemic intoxication, especially those which release free formaldehyde or organic solvents into the atmosphere. Adhesives should be handled in well ventilated premises and sources of vapour emission should be equipped with exhaust ventilation. Employees should be provided with gloves, protective creams, respirators and eye protection when necessary.

The moving parts, especially blades, of veneer slicing, jointing and clipping machines should be fully guarded. Two-hand controls may be necessary.

Finishing hazards

Surface finishing. Solvents used for carrying the sprayed pigments or for thinning can include a wide variety of volatile organic compounds which may reach toxic and explosive concentrations in the air. In addition, many pigments are toxic by inhalation of spray mist (e.g., lead, manganese and cadmium pigments). Wherever dangerous concentrations of vapour or mist can occur, use exhaust ventilation (e.g., spray painting in a booth) or use water sprays. All sources of ignition, including fires, electrical equipment and static electricity, should be eliminated before any operations begin.

An active hazardous material communication programme should be in place to alert employees to all hazards created by toxic, reactive, corrosive and/or ignitable finish, glue and solvent chemicals and the protective measures that should be taken. Eating in the presence of these chemicals should be prohibited. Proper storage of flammables and proper disposal of soiled rags and steel wool which could cause spontaneous ignition are imperative.

Fire prevention. In view of the highly flammable nature of wood (especially in the form of dust and shavings) and of the other items found in a woodworking plant (such as solvents, glues and coatings), the importance of fire prevention measures cannot be overemphasized. Measures include:

  • installing automatic wood-dust and shaving collection equipment on saws, planers, moulders and so on, which transport the waste to storage silos pending disposal or recovery
  • prohibiting smoking at the workplace and eliminating all sources of ignition (e.g., open flames)
  • ensuring regular clean-up procedures of deposited dust and shavings
  • adequate maintenance of machines to prevent occurrences such as the overheating of bearings
  • installation of fire barriers, sprinkler systems, fire extinguishers, fire hoses and a crew trained to use this equipment
  • proper storage of flammables
  • explosion-proof electrical equipment where needed.

 

Environmental and Public Health Concerns

The production of finished products from wood can be done without long-range environmental damage. The harvesting of trees can be done in such a manner that new growth can replace what is cut. Major deforestation such as has been the case in rain forests can be discouraged. Waste products from the machining of wood (i.e., sawdust, wood chips) can be used in chipcore or as fuel.

While there are solid waste and process wastewater implications for the woodworking industry, the major concerns are the air emissions resulting from the use of waste wood as fuel and from solvent-intensive finishing operations. Wood-fired boilers are commonly used in drying operations, while many of the finishing materials are applied by spray. In both instances, engineering controls are required to reduce air-borne particulates and recover and/or incinerate the volatile compounds.

Controls should result in operators being exposed to less toxic chemicals as less hazardous substitutes are found. Use of water-based finishes instead of solvent-based will decrease fire hazards.

 

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Read 20678 times Last modified on Monday, 05 September 2011 19:01
More in this category: « General Profile Routing Machines »

Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides